1. Field of the Invention
This application claims priority from Japanese Patent Application No. 2007-334547, filed Dec. 26, 2007, the disclosure of which is herein incorporated in its entirety. The present invention relates to a transmission characteristic adjustment device, a circuit substrate, and a transmission characteristic adjustment method that adjust a transmission characteristic between a transmission element and a reception element having a transmission path interposed therebetween. In particular, the present invention relates to a transmission characteristic adjustment device, a circuit substrate, and a transmission characteristic adjustment method that monitor deterioration of waveform quality in an input of a reception element of a signal transmission system with a window width in a time axis direction measured by using a multiphase CLK as an index, and use a result of the monitoring to adjust a transmission characteristic.
2. Description of the Related Art
In recent years, along increase in speed of signal transmission, there is a tendency that a margin thereof (waveform margin) becomes smaller. Accordingly, there has been increased need for sequential adjustment of a transmission characteristic with respect to proper locations on a device, not only in design and evaluation stages.
In contrast, a technique which has been conventionally provided adopts a system that adjusts any circuit element to adjust a transmission characteristic while monitoring an error factor. For example, as a reference document, there is a Patent Document such as Jpn. Pat. Appln. Laid-Open Publication No. 2003-032187.
However, when a circuit element is adjusted while an error factor is monitored, an error factor of a certain degree needs to be tolerated. Accordingly, there has been a problem that the conventional technique can only be applied to a system that can tolerate an error factor of a certain degree.